Japanese Patent Publication Laid-Open No. 2008-176515 discloses a wireless communication system (wireless transmission system) including a plurality of battery-powered wireless terminals (wireless devices). In the wireless communication system, each of wireless terminals performs intermittent reception operation of activating its reception circuit at a predetermined intermittent reception interval. The wireless terminal checks whether or not the wireless terminal receives a desired electric wave (e.g., a wireless signal transmitted from another wireless terminal) while the reception circuit operates. When the reception circuit receives the wireless signal, the wireless terminal performs operation in response to contents of the received wireless signal. Therefore, according to the above wireless communication system, in contrast to an instance where the wireless terminal always operates its reception circuit, it is possible to reduce an amount of consumed power.
However, each of the wireless terminals performs the intermittent reception operation independently from the other wireless terminals. Thus, all of the wireless terminals destined to receive the wireless signal may fail to receive the wireless signal. When the wireless terminal failed to receive the wireless signal, the wireless terminal has no opportunity to receive the wireless signal unless the wireless signal is transmitted again.
In other words, the above wireless communication system is likely to suffer from a prolonged time for reception of the wireless signal by all the wireless terminals which are destined to receive the wireless signal.